Routing can cope with question marks in URL

The routing routine failed when e.g. a third party added normal
"question mark GET parameters" to the URL. With this commit these
parameters are removed before the URL parts are separated.

I had this problem when I integrated Facebook login. After the login of the user Facebook will redirect him or her to [myURL]?code=[someHash] and this used to break PEPs routing system.

I proposed the same change already to PIP, but it does not look like there is much going on over there.